The Netpage system involves the interaction between a user and a computer network (or stand alone computer) via a pen and paper based interface. The ‘pen’ is an electronic stylus with a marking or non-marking nib and an optical sensor for reading a pattern of coded data on the paper (or other surface).
The Netpage pen is an electronic stylus with force sensing, optical sensing and Bluetooth communication assemblies. A significant number of electronic components need to be housed within the pen casing together with a battery large enough to provide a useful battery life. Despite this, the overall dimensions of the pen need to be small enough for a user to manipulate it as they would a normal pen.
The force sensor circuitry typically utilizes a piezo-electric element. The sensor deflects a small amount when it is subjected to a force. If the force applied to the sensor exceeds the elastic limits of the sensor, and in particular the delicate crystal element, the sensor can break. Protective stops or buffers can be used so that a static input force can not excessively deform the sensor. However, shock loading can still damage in the sensor, particularly if the Netpage pen is dropped on its nib.